Front panel layout of Transvolt Model 9154B
b. Monitoring of internal temperature. All four arms of a Wheatstone
bridge are located inside the inner enclosure.
One of the arms of the
bridge is a thermistor in close proximity to the standard cells; another arm
of the bridge is shunted by an adjustable resistor located on the front
panel of the enclosure, and calibrated over a 0.025C range with resolution
This bridge is not intended for the measurement of absolute
It is intended only for the measurement of temperature
deviation from nominal. When the cell voltages are certified, the operating
temperature, as indicated by the dial is recorded, and thereafter it is
necessary to know only that the cell temperature is unchanged.
indicated by the thermistor bridge balance point.
(1) To check the cell temperature, a galvanometer is connected to the
terminals marked GALV and, with the BRIDGE switch at OFF, the galvanometer is
set to zero. The BRIDGE switch is switched to ON and the front panel dial